HR: 16:30h
AN: B44A-05    [Abstracts]
TI: Flood Tide Transport of Blue Crab Postlarvae: Limitations in a Lagoonal Estuary
AU: * Cudaback, C
EM: cncudaba@ncsu.edu
AF: Department of Marine Earth and Atmospheric Sciences, Campus Box 8208 North Carolina State University, Raleigh, NC 27695 United States
AU: Eggleston, D
EM: eggleston@ncsu.edu
AF: Department of Marine Earth and Atmospheric Sciences, Campus Box 8208 North Carolina State University, Raleigh, NC 27695 United States
AB: Blue crabs, an important commercial species, spend much of their life in estuaries along the east coast. The larvae spawn at or near the ocean, but the juveniles mature in the lower salinity waters of the estuary. It is generally believed that blue crab postlarvae migrate into near surface waters on flood, possibly cued by increasing salinity, and return to the bottom on ebb. Over several tidal cycles, the postlarvae travel a significant distance up-estuary. This model applies quite well to Chesapeake Bay, which has a strong along-estuary salinity gradient and large tides, but may not apply as well to Pamlico Sound, where circulation and salinity are more wind-driven than tidal. A recently completed study (N. Reyns, PhD), indicates that postlarval blue crabs use flood tides and wind-driven currents to cross Pamlico Sound. This study was based on observations with good spatial coverage, but limited vertical and temporal resolution. We have recently completed a complementary study, sampling crab larvae around the clock at four depths at a single location. Preliminary results from the new study suggest that the crab postlarvae do swim all the way to the surface, on flood only, and that flood currents are strongest slightly below the surface. These observations suggest the utility of flood tide transport in this system. However, near bottom salinity does not seem to be driven by tides; at this point it is unclear what cue might trigger the vertical migration of the postlarvae.
DE: 4235 Estuarine processes
SC: Biogeosciences [B]
MN: 2005 Joint Assembly